U.S. patent number 7,792,421 [Application Number 11/550,119] was granted by the patent office on 2010-09-07 for triaxial snubber assembly.
This patent grant is currently assigned to Tessera MEMS Technologies, Inc.. Invention is credited to Kumaraswamy Jayaraj, Shi-Sheng Lee, Davy Tong.
United States Patent |
7,792,421 |
Tong , et al. |
September 7, 2010 |
**Please see images for:
( Certificate of Correction ) ** |
Triaxial snubber assembly
Abstract
A method and system for mitigating undesirable motion of the
optics of a camera are disclosed. The system can include a stage
and snubber assembly for defining motion of the camera optics. The
stage and snubber assembly can include a stage assembly having a
stage to which the optics are attachable, at least one wing formed
upon the stage, and a snubber assembly configured to cooperate with
the wing(s) so as to limit motion of the stage substantially to the
desired direction of travel of the camera optics.
Inventors: |
Tong; Davy (Temple City,
CA), Lee; Shi-Sheng (Arcadia, CA), Jayaraj;
Kumaraswamy (San Diego, CA) |
Assignee: |
Tessera MEMS Technologies, Inc.
(Arcadia, CA)
|
Family
ID: |
42669703 |
Appl.
No.: |
11/550,119 |
Filed: |
October 17, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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11268849 |
Jan 12, 2010 |
7646969 |
|
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60657261 |
Feb 28, 2005 |
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Current U.S.
Class: |
396/144;
359/823 |
Current CPC
Class: |
G02B
7/003 (20130101); H04N 5/2254 (20130101); G03B
3/02 (20130101); G02B 7/023 (20130101); H04N
5/23287 (20130101); G03B 17/02 (20130101) |
Current International
Class: |
G03B
3/00 (20060101); G02B 7/02 (20060101) |
Field of
Search: |
;396/55,72,79,89,133,136,343,529,144 ;33/1M ;108/140,143
;348/208.99,208.7,208.11 ;310/309 ;359/823 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Perkey; W. B.
Assistant Examiner: Phan; Minh Q
Attorney, Agent or Firm: Haynes and Boone, LLP
Parent Case Text
RELATED APPLICATIONS
This patent application is a continuation-in-part (CIP) patent
application of U.S. patent application Ser. No. 11/268,849, filed
Nov. 8, 2005, and entitled CAMERA SNUBBER ASSEMBLY, now U.S. Pat.
No. 7,646,969, issued Jan. 12, 2010, the entire contents of which
are hereby expressly incorporated by reference. U.S. patent
application Ser. No. 11/268,849 claims the benefit of the priority
date of U.S. provisional patent application Ser. No. 60/657,261,
filed on Feb. 28, 2005 and entitled AUTOFOCUS CAMERA pursuant to 35
USC 119, the entire contents of which are hereby expressly
incorporated by reference.
Claims
The invention claimed is:
1. A system for controlling motion, the system comprising: a stage
having four corners, a generally planar upper surface, front and
rear edges resiliently supported for generally rectilinear movement
of the upper surface along a motion control axis lying in the plane
of the upper surface and perpendicular to the front and rear edges
of the stage, and opposite side edges, each having a laterally
extending wing formed thereon and defining a cutout at each of the
four corners of the stage; and, a snubber assembly surrounding the
periphery of the stage and having four mesas formed thereon, each
of the mesas extending generally perpendicular to the plane of the
upper surface of the stage and into a corresponding one of the
cutouts of the stage and being configured to cooperate with
adjacent edges of the stage and the wings so as to limit movement
of the upper surface of the stage to substantially rectilinear
movement along the motion control axis.
2. A stage and snubber assembly for defining motion of miniature
camera optics, the stage and snubber assembly comprising: a stage
assembly comprising a stage having four corners, a generally planar
upper surface to which the optics are attachable, front and rear
edges resiliently supported for generally rectilinear movement of
the upper surface along a motion control axis lying in the plane of
the upper surface and perpendicular to the front and rear edges of
the stage, and opposite side edges, each having a laterally
extending wing formed thereon and defining a cutout at each of the
four corners of the stage; and, a snubber assembly surrounding the
periphery of the stage and having four mesas formed thereon, each
of the mesas extending generally perpendicular to the plane of the
upper surface of the stage and into a corresponding one of the
cutouts of the stage and being configured to cooperate with
adjacent edges of the stage and the wings so as to limit movement
of the upper surface of the stage to substantially rectilinear
movement along the motion control axis.
3. The stage and snubber assembly as recited in claim 2, wherein
movement of the stage effects focusing of the camera.
4. The stage and snubber assembly as recited in claim 2, wherein
the snubber assembly comprises two portions that are configured to
sandwich the stage assembly therebetween.
5. The stage and snubber assembly as recited in claim 2, wherein
the snubber assembly comprises two portions that are configured to
sandwich the stage assembly therebetween and each of the two
portions comprises two of the mesas.
6. The stage and snubber assembly as recited in claim 5, wherein
the snubber assembly comprises two substantially identical
portions.
7. The stage and snubber assembly as recited in claim 2, wherein
the mesas are formed integrally with the snubber assembly.
8. The stage and snubber assembly as recited in claim 2, wherein
the snubber assembly comprises two substantially identical portions
that are configured to capture the stage assembly therebetween and
each of the two portions comprises two mesas formed integrally
therewith.
9. The stage and snubber assembly as recited in claim 2, wherein
the snubber assembly comprises two substantially identical portions
that are configured to capture the stage assembly therebetween,
each of the two portions comprises two mesas formed integrally
therewith, and the portions and the mesas comprise a resilient
material.
10. The stage and snubber assembly as recited in claim 2, wherein
the snubber assembly comprises two substantially identical portions
that are configured to capture the stage assembly therebetween,
each of the two portions comprises two mesas formed integrally
therewith, and the portions and the mesas comprise a material that
is softer than a material of the stage assembly.
11. The stage and snubber assembly as recited in claim 2, wherein
the snubber assembly comprises two substantially identical portions
that are configured to capture the stage assembly therebetween,
each of the two portions comprises two mesas formed integrally
therewith, and the portions and the mesas comprise a material that
is more resilient than a material of the wing(s).
12. The stage and snubber assembly as recited in claim 2, wherein
the snubber assembly comprises two substantially identical portions
that are configured to capture the stage assembly therebetween,
each of the two portions comprises two mesas formed integrally
therewith, and the portions and the mesas comprise a polymer
material.
13. A camera, comprising the stage and snubber assembly as recited
in claim 2.
14. A cellular telephone, comprising the camera as recited in claim
13.
Description
TECHNICAL FIELD
The present invention relates generally to cameras. The present
invention relates more particularly to a snubber assembly for
limiting the motion of optical elements in a miniature camera, such
as a miniature camera that is suitable for use in a cellular
telephone.
BACKGROUND
Miniature cameras are well known. Miniature cameras are widely used
in contemporary cellular telephones. They are also used in other
devices, such as laptop computers and personal digital assistants
(PDAs). Miniature cameras can even be used as stand alone devices
for such applications as security and surveillance.
Contemporary miniature cameras, such as those used in cellular
telephones, are fixed focus cameras. That is, the focus of the
cameras is preset. The camera has a small enough aperture so as to
provide sufficient depth of field such that focus is generally
acceptable over a wide range of distances. However, such stopping
down of the camera severely limits it's use in low light
conditions.
Stopping down also limits resolution since it tends to inhibit the
use of higher pixel count imagers. As those skilled in the art will
appreciate, larger apertures allow higher imager pixel counts, but
require the use of variable focus.
Variable focus necessitates the use of movable optics. However,
movable optics suffer from inherent disadvantages. Foremost among
these disadvantages is the size of the mechanisms required to
effect and control movement of the movable optics. For example, the
structures used to control the movement of optics in larger cameras
are simply too large for use in many miniature cameras. As such, it
is desirable to provide miniature structures for controlling motion
in miniature cameras.
BRIEF SUMMARY
A method and system for controlling, i.e., limiting, the motion of
miniature components, such as the optics of a camera, are
disclosed. The system can comprise a stage and a snubber assembly
for controlling the motion of the stage in six degrees of freedom.
Camera optics can be attached to the stage to facilitate focusing
and/or zooming. According to one embodiment of the present
invention, the stage can move freely in one degree of freedom
within a limited range of motion. Thus, the movement of the stage
can be used for moving optics so as to effect focus and/or zoom,
for example.
For example, the snubber assembly can readily permit movement in
one translational degree of freedom while substantially limiting
motion in the other five degrees of freedom. This is accomplished
in a manner that facilitates focusing and/or zooming of a camera
while inhibiting misalignment of the optics and while also
providing some protection against shock and vibration.
Such motion control can be achieved while mitigating the costs
associated with precision manufacturing of the snubber assembly.
More particularly, the precision with which manufacturing of the
snubber assembly is performed can be reduced by relying upon
physical features of a stage assembly to facilitate precise
positioning of physical features of the snubber assembly. That is,
positioning of at least some features of the snubber assembly are
dependent upon corresponding features of the stage assembly such
that desirable alignment of the snubber assembly with respect to
the stage assembly results.
According to one embodiment of the present invention, mesas of the
snubber assembly abut stationary or fixed portions of the stage
assembly so as to define, at least in part, one or more horizontal
gaps between the stage and the snubber assembly. The size of these
horizontal gaps determines the limits of horizontal movement of the
stage.
Similarly, shims of the snubber assembly abut the fixed portion of
the stage assembly so as to define, at least in part, one or more
vertical gaps between the stage and the snubber assembly. The size
of these vertical gaps determines the limits of vertical movement
of the stage.
Undesirable rotations of the stages can also be limited by the
snubber assembly of the present invention. Pitching motion
(rotation about the horizontal or lateral axis, which is orthogonal
to the direction of travel) results in up and down vertical motion
of the front and back ends of the stage. Similarly, yaw motion
(rotation about a vertical axis) results in horizontal or lateral
motion of the front and back ends of the stage. Similarly, roll
motion (rotation about an axis along the direction of travel)
results in vertical motion of the sides of the stage. Since the
snubber assembly inhibits vertical motion of the front and back
ends of the stage, lateral motion of the front and back ends of the
stage, and vertical motion of the sides of the stage, these three
rotations are substantially inhibited.
According to one aspect of the present invention, smaller features
of the snubber assembly are manufactured with higher tolerances,
while larger features of the snubber assembly can be manufactured
with lower tolerances. It is not necessary to manufacture larger
features of the snubber assembly with higher tolerances and thus
manufacturing costs are therefore substantially reduced.
According to one embodiment of the present invention, a system for
controlling motion, such as the motion of camera optics, comprises
a stage having at least one wing formed thereon and a snubber
assembly having a plurality of mesas formed thereon. The mesas can
be configured such that they cooperate with the wing(s) so as to
control motion of the stage.
More particularly, a stage and snubber assembly for defining motion
of miniature camera optics can comprise a stage assembly comprising
a stage to which the optics are attachable, at least one wing
formed upon the stage, and a snubber assembly configured to
cooperate with the wing(s) so as to limit motion of the stage in
five degrees of freedom while facilitating a substantially greater
amount of motion in a sixth degree of freedom.
The stage can be configured to move in a generally linear fashion
so as to effect focusing of the camera. The wing(s) can be formed
upon each of two opposing sides of the stage. The wing(s) can be
formed upon each of two opposing sides of the stage such that the
wing(s) extend in a direction that is generally perpendicular to
the direction of travel of the stage.
The snubber assembly can comprise a plurality of mesas that are
configured to cooperate with the wing(s) so as to limit movement of
the stage. The snubber assembly can comprise two portions, e.g., an
upper portion and a lower portion, that are configured to capture
the stage assembly therebetween. Each of the two portions can
comprise two mesas that are configured to cooperate with the
wing(s) so as to limit movement of the stage.
More particularly, the snubber assembly can comprise two
substantially identical portions that are configured to capture the
stage assembly therebetween. Each of the two portions can comprise
two mesas.
The snubber assembly can comprise a plurality of mesas. For
example, the snubber assembly can comprise two, four, six, or eight
mesas. Indeed, the snubber assembly can comprise any desired number
of mesas. The mesas can be either formed separately from the
snubber assembly of can be formed integrally therewith. Each of the
two portions of the snubber assembly can comprise two mesas formed
integrally therewith.
The two portions of the snubber assembly and the mesas comprise a
resilient material. For example, the mesas (as well as the rest of
the snubber assemblies) can comprise a material that is softer
and/or more resilient than a material of which the stage assembly
is constructed. More particularly, the mesas (as well as the rest
of the snubber assemblies) can comprise a material that is more
resilient than the material of which the wing(s) are constructed.
For example, the mesas (as well as the rest of the snubber
assemblies) can comprise a polymer material.
The mesas can be configured to abut the wing(s) so as to limit
movement of a stage of the stage assembly. The mesas can be
configured to abut the wing(s) when the stage moves more than a
predetermined distance in its direction of travel. The mesas can be
configured to abut a portion of the stage other than the wing(s)
when the stage moves transversely more than a predetermined
distance. The snubber assembly can capture a portion of the stage
such that the stage abuts the snubber assembly when the stage moves
axially more than a predetermined distance.
According to an exemplary embodiment of the present invention, a
camera, such as a camera of a cellular telephone or another
personal electronic device, comprises a stage and snubber assembly
for defining motion of miniature camera optics. The stage and
snubber assembly can comprise a stage assembly comprising a stage
to which the optics are attachable and can also comprise at least
one wing.
According to an exemplary embodiment of the present invention, a
method for controlling motion of camera optics comprises abutting
mesas of a snubber assembly with wings of a stage when the stage
moves more than a predetermined distance in its direction of
travel, abutting the mesas of the snubber assembly with portions of
the stage other than the wings when the stage moves transversely
more than a predetermined distance, and abutting the snubber
assembly with the wings when the stage moves up or down more than a
predetermined distance.
This invention will be more fully understood in conjunction with
the following detailed description taken together with the
following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is perspective top view of a stage and snubber assembly
according to an exemplary embodiment of the present invention;
FIG. 2 is a top perspective cross-sectional view of the stage and
snubber assembly taken along line 2 of FIG. 1;
FIG. 3 is an outboard perspective view of a snubber portion of FIG.
1;
FIG. 4 is an inboard perspective view of the snubber portion of
FIG. 3;
FIG. 5 is a top or bottom (both are identical) perspective view of
the stage assembly of FIG. 1;
FIG. 6 is an enlarged fragmentary view of the interface of the top
snubber, the bottom snubber, and the stage, taken within line 5 of
FIG. 2;
FIG. 7 is a top perspective view of a stage and snubber assembly
according to another exemplary embodiment of the present invention;
and
FIG. 8 is a top view of the stage assembly of FIG. 7, showing two
mesas of a snubber assembly positioned with respect thereto.
Embodiments of the present invention and their advantages are best
understood by referring to the detailed description that follows.
It should be appreciated that like reference numerals are used to
identify like elements illustrated in one or more of the
figures.
DETAILED DESCRIPTION OF THE INVENTION
A method and system for defining the motion of a stage is
disclosed. The stage is suitable for mounting camera optics upon.
For example, focus and/or zoom lenses can be mounted to the stage.
According to one aspect of the present invention, motion of the
stage in six degrees of freedom is controlled. More particularly,
motion in five degrees of freedom is substantially limited, while
motion in one translational degree is freedom is facilitated. For
example, translational motion in two degrees of freedom can be
limited to approximately 10 microns, rotational motion in three
degrees of freedom can be limited to approximately 0.1 degrees, and
translational motion in one degree of freedom in excess of one
millimeter can be facilitated.
In this manner, the stage can be permitted to translate along one
axis sufficiently so as to effect focusing and/or zooming, while
not being permitted to translate sufficiently along other axes or
to rotate about any axis sufficiently so as to effect misalignment
of the optics to a degree that would substantially degrade
performance of the camera. Moreover, the snubber assembly of the
present invention can be configured so as to only effect motion
control when the stage is caused to move outside of a set of
predefined ranges. That is, the snubber assembly can be configured
such that it has no effect until the stage experiences a shock or
abnormal operation that would otherwise cause it to move in an
undesirable manner. When this happens, the snubber assembly can
then restrict motion of the stage to within the desired ranges, so
as to prevent the misalignment of optics, for example. Thus, during
normal operation, the snubber assembly can have little or no
effect.
One way to make a snubber assembly that limits movement of a stage
is to use close (precise) tolerances to assure that all features of
the snubber assembly are properly located. However, such
construction of the snubber assembly requires that the
comparatively large structures thereof be manufactured with the
same close tolerances as the comparatively small structures. As
those skilled in the art will appreciate, while it is comparatively
easy to manufacture smaller structures with such close tolerances,
it becomes increasingly difficult to do so as the size of the
structures increases. That is, deviations from desired dimensions
tend to accumulate across larger distances, making it difficult to
maintain close tolerances. According to one aspect of the present
invention, a different approach results in a snubber that precisely
limits the motion of a stage.
According to one aspect of the present invention, critical gap
dimensions are obtained by manufacturing only selected small
structures of the snubber assembly with comparatively higher
precision, while manufacturing the rest (particularly the larger
dimensions) of the snubber assembly with substantially lower
precision. Because the larger dimensions are manufactured with
lower precision, the positions of the smaller structures of the
snubber assembly are not precise.
This lack of precision in the location of the smaller structures
can be compensated for by using portions of the stage assembly to
precisely position the smaller structures. That is, the smaller
structures of the snubber assembly are effectively keyed into
position using precisely formed portions of the stage assembly.
Thus, the position of snubbers manufactured, at least in part, with
a comparatively low amount of precision is determined by a portion
of a stage assembly that is manufactured with a comparatively high
amount of precision.
Referring now to FIGS. 1 and 2, a stage assembly 10 (better shown
in FIG. 5) is sandwiched between two portions, 11 and 12 (better
shown in FIGS. 3 and 4), of a snubber assembly 13, according to one
embodiment of the present invention. The stage assembly 10 and the
snubber assembly 13 can be generally planar structures, formed from
silicon, for instance. Stage assembly 10 and/or snubber assembly 13
can alternatively be formed from another material, such as plastic
or metal. Alternatively, both the stage assembly 10 and the snubber
assembly 13 can be formed from either plastic or silicon or any
other desired material or combination of materials.
Stage assembly 10 comprises a stage 41 that moves back-and-forth,
so as to facilitate movement of optics for focusing and/or zooming,
for example. Stage assembly 10 further comprises a frame 42 that
generally surrounds stage 41 (as best seen in FIG. 5). Frame 42 is
fixed in position with respect to snubber assembly 13 and thus does
not move. Arrow 16 shows the back-and-forth directions of motion of
stage 41 with respect to frame 42 (better shown in FIG. 5) and with
respect to snubber assembly 13. Snubber assembly 13 facilitates
such back-and-forth motion of stage 41 while substantially
inhibiting all other motions of stage 41.
Referring now to FIGS. 3 and 4, each portion 11, 12 of snubber
assembly 13 can be a generally planar and generally rectangular
structure. Snubber assembly 13 can comprise two biasing members 31
and 32 that function as springs to bias two sides 33 and 34
outwardly, so as to cause them to contact portions (surfaces 56 and
57 as shown in FIG. 6) of frame 42 in a manner that advantageously
positions critical features of snubber assembly 13, as discussed in
detail below. Alternatively, the inherent resiliency of snubber
assembly 13 can effect such biasing.
Each biasing member 31, 32 can comprise an inboard member 35, an
outboard member 36, and two side members 37 and 38 that are
configure to cooperate so as to provide spring tension that moves
the sides 33 and 34 outwardly after sides 33, 34 have been pushed
inwardly (such as when stage assembly 10 is being installed
therebetween). That is, the rectangle defined by an inboard member
35, an outboard member 36, and two side members 37 and 38 can
deform so as to define a parallelogram that provides spring
tension. Each portion 11, 12 of snubber assembly 13 further
comprises structural features that cooperate with stage assembly 10
to define tolerances or spacings between snubber assembly 13 and
stage 41, as discussed in detail with reference to FIG. 6
below.
With particular reference to FIG. 4, each portion 11, 12 of snubber
assembly 13 may have formed upon an inboard (snubber assembly 10
contacting) surface thereof a plurality of mesas 51, shims 61, and
stops 58, the functions of which are discussed in detail with
reference to FIG. 6 below. Although mesas are shown formed upon
both of the snubber assemblies, mesas may alternatively be formed
upon only one of the snubber assemblies. Mesas can be formed upon
both snubber assemblies so as to maintain symmetry (so as to allow
a single part to be capable of being used as either an upper
snubber or a lower snubber. However, such symmetry is not a
requirement. Therefore, a single mesa (which will generally have
approximately twice the height of the mesas shown in FIG. 4) can
replace each complimentary pair of mesas.
Referring now to FIG. 5, stage assembly 10 comprises a movable
portion or stage 41 and a fixed portion or frame 42. Stage 41 can
be a generally planar, generally rectangular structure. Optics are
attachable, either directly or indirectly, to stage 41.
Stage 41 can move in response to a motor or actuator, such as to
effect focusing and/or zooming. For example, an optics assembly
(not shown) can be attached to stage 41 via apertures 43a-43d.
Frame 42 can similarly be a generally planar and generally
rectangular structure that can substantially surround a periphery
of stage 41. Frame 42 can be movably attached to stage 41 via
flexure assemblies 45 and 46. Flexure assemblies 45 and 46 can
preferentially facilitate movement of stage 41 in one desired
translational degree of freedom, i.e., in the back-and-forth
directions of arrow 16 of FIG. 1. Snubber assembly 13 can limit
movement of stage 41 that is beyond the one desired translation
degree of freedom.
Stage 41, as well as frame 42, snubber assembly 13, and other
components of the present invention, can be of any desired shape
and/or configuration. Stage assembly 10 can be formed monolithicly,
such as via the etching or milling of a single piece of silicon or
other material. Similarly, snubber assembly 13 can also be formed
monolithicly. Alternatively, stage assembly 10 and/or snubber
assembly 13 can be formed in any other desired manner using any
desired material. Indeed, the reduced precision needed by snubber
assembly 13 according to one aspect of the present invention allows
snubber assembly 13 to be formed of plastic using low a precision
manufacturing process.
Snubber assembly 13 defines limits to movement of stage 41, so as
to inhibit movement in five other degrees of freedom for which it
is desirable to restrict movement of stage 41. Such limitations on
the movement of stage 41 tend to maintain desired alignment of
components, such as optics. The limitations are also desirable, for
example, in the event of shock or vibration that would other cause
stage 41 to move in a manner that may cause damage to itself or
other components, e.g., lenses of a camera. Thus, the stage, and
consequently the camera optics, can be permitted to move in a
manner that facilitates desired functionality, e.g., focusing
and/or zooming, while also being restrained in a manner that
mitigates undesirable malfunctioning (misalignment of optics) and
damage.
Referring now to FIG. 6, exemplary structures of stage assembly 10
and snubber assembly 13 that limit motion of stage 41 in five
degrees of freedom while facilitating substantially more motion in
a sixth degree of freedom (as indicated by arrow 16 in FIG. 1) are
shown. Each portion 11, 12 of snubber assembly 13 comprises
features such as mesas 51, 52, shims 53, 54, and stops 58, 59 that
define limits to the movement of stage 41 in five degrees of
freedom while permitting unrestricted movement of stage 41 in one
degree of freedom.
Mesas 51, 52, shims 53, 54, and stops 58, 59 are formed precisely.
They are also precisely positioned by keying to or abutting
precisely formed portions of frame 42, so that they are, in-turn,
precisely positioned themselves and are thus suitable for defining
limits to the movement of stage 41.
In this manner, the limits to the movement of stage 41 can be
defined with greater precision than the precision with which the
overall snubber assembly 13 is manufactured because the snubber
assembly 13 cooperates with the frame 42 of the stage assembly 10
to define positioning of the structures that limit motion of stage
41 and because frame 42 is manufactured with sufficient precision
so as to facilitate such definition of these positions.
More particularly, the width, Dimension A, of each mesa 51, 52
together with the distance between stage 41 and frame 42, Dimension
C, defines the size of the horizontal gap, Dimension B, between
stage 41 and snubber assembly 13. Since the width of each mesa 51,
52, Dimension A, and the distance between the stage 41 and the
frame 42, Dimension C, can be easily controlled, the horizontal
gap, Dimension B, can likewise be easily controlled. The distance
between the stage 41 and frame 42, Dimension C, is controlled by
precisely manufacturing the overall dimensions of stage assembly
10. The width of mesa 51, 52 only requires precision in the
manufacturing of a comparatively small portion of the snubber
assembly 13, i.e., each mesa 51, 52 itself. It does not require
that the position of each mesa 51, 52 be precisely determined
during manufacturing of snubber assembly 13.
Positioning of each mesa 51, 52 is determined by its contact with
frame 42 at surfaces 56 and 57. Contact at surfaces 56 and 57 is
effected by the outward biasing of side members 33 and 34 of each
portion 11, 12 of snubber assembly, as described above. Since frame
42 of snubber assembly 13 is manufactured with precision, this
contact point is precisely located. Thus, the size of the
horizontal gap, Dimension B, between the stage 41 and the snubber
assembly 13 can be controlled without requiring that the overall
manufacturing tolerances of snubber assembly 13 be precise.
Similarly, the thickness, Dimension D, of each shim 53, 54 together
with the thickness, Dimension E, of frame 42, defines the size of
each horizontal gap, such as Dimension F, between stage 41 and the
stops 58, 59 of snubber assembly 13. Shims 53, 54 contact frame 42
at surfaces 61, 62 thereof. This contact is effected by attachment
of the upper portion 11 to the lower portion 12 of snubber assembly
13 by any desired means, such as by adhesive bonding. Upper portion
11 and lower portion 12 can be attached to one another directly, or
can be attached to one another indirectly, such as by adhesively
bonding upper portion 11 and lower portion 12 to stage 41 or by
using detents or the like to attach upper portion 11 and lower
portion 12 to stage 41.
There are two such vertical gaps on each of the two sides of stage
41. On each side of stage 41, one vertical gap is above stage 41
and one vertical gap is below stage 41. Since the thickness,
Dimension D, of each shim 53, 54, and the thickness, Dimension E,
of frame 42 can be precisely controlled, each vertical gap,
Dimension F, can also be precisely controlled. The thickness,
Dimension D, of each shim can be controlled by precisely
manufacturing a small portion of the snubber assembly 13. The
thickness, Dimension E, of frame 42 can be precisely controlled
during manufacture thereof. As with the horizontal gap, Dimension
B, the distance between stage 41 and frame 42 defining each one of
the vertical gaps, such as Dimension F, is controlled by precisely
manufacturing the overall dimensions of stage assembly 10. The
thickness, Dimension D, of shims 53, 54 only requires precision in
the manufacturing of a comparatively small portion of snubber
assembly 13, i.e., each shim 53, 54 itself. Again, it does not
require that the position of each shim 53,54 be precisely
determined during manufacturing of snubber assembly 13.
It is worthwhile to note that a vertical gap, Dimension G, is
provided between mesas 51 and 52 to insure that they do not contact
one another and thereby interfere with proper positioning of shims
53 and 54 (and consequently with the definition of the vertical
gaps between stage 41 and snubber assembly 13, such as Dimension
F). The size of the vertical gap, Dimension G, is not crucial.
For example, Dimension A can be approximately 300 microns,
Dimension B can be approximately 10 microns, Dimension C can be
approximately 310 microns, Dimension D can be approximately 25
microns, Dimension E can be approximately 300 microns, Dimension F
can be approximately 10 microns, and Dimension G can be
approximately 25 microns. However, as those skilled in the art will
appreciate, various other values for these dimensions are likewise
suitable and the dimensions used will depend upon the specific
application.
Thus, only the mesas 51, 52, shims 53, 54 and stops 58, 59 of
snubber assembly 13 need be precisely manufactured. These are
comparatively small portions of snubber assembly 13 and can thus be
precisely manufactured with relative ease. The overall dimensions
of snubber assembly 13 do not require such precision. Moreover,
according to one aspect of the present invention, close tolerances
(Dimensions B and F, for example) between the stage 41 and the
snubber assembly 13 are obtained without requiring that the larger
dimensions of snubber assembly be precisely controlled.
Rather, the larger dimensions of stage assembly 10 are controlled,
as well as the smaller dimensions of critical structures of snubber
assembly 13 that cooperate with stage assembly 10 to determine the
dimensions of critical gaps therebetween (such as Dimensions B and
F). In this manner, the manufacturing process of the stage and
snubber assembly of the present invention is simplified and the
cost thereof is mitigated.
Optionally, channels 63 and 64 are formed in upper 11 and lower 12
portions of snubber assembly 13. Channels 63 and 64 mitigate the
likelihood of edges 81 and 82 (FIG. 5) of stage 41 contacting upper
11 and lower 12 portions of snubber assembly 13 and causing damage
to stage 41 and/or snubber assembly 13.
Similarly, cutouts 71-74 (best shown in FIG. 3) can be formed in
upper 11 and lower 12 portions of snubber assembly 13 to inhibit
corners 86-89 (FIG. 5) from contacting upper 11 and lower 12
portions of snubber assembly 13 and causing damage to stage 41
and/or snubber assembly 13.
In operation, stage 41 can move substantially in one translational
degree of freedom, as indicated by arrow 16 of FIG. 1. For example,
optics mounted to stage 41 can be moved in these directions to
effect focusing and/or zooming of a camera. Such movement of stage
41 results in compression of one set of flexures (such as flexures
45 of FIG. 5), while simultaneously resulting in expansion of the
other set of flexures (such as flexures 46 of FIG. 5). The amount
of movement along this one degree of freedom is limited by the
configuration of flexures 45, 46 and by the size of frame 42, not
by snubber assembly 13.
It is also worthwhile to note that the stage and snubber assembly
of the present invention can be configured such that during normal
operation stage 41 does not contact snubber assembly 13. Thus, the
snubbing action that can be provided by mesas 51, 52 and stops 58,
59 can be for extraordinary circumstances, such as when the device
is accidentally dropped. However, in such extraordinary
circumstances, the snubber assembly of the present invention can
prevent excessive motion in any combination of degrees of
freedom.
Movement in the five restricted degrees of freedom is comparatively
limited. Translation of stage 41 from side-to-side (toward and away
from mesas 51, 52) is limited by mesas 51, 52. That is, when stage
41 moves from side-to-side by an amount greater than Dimension B,
it contacts mesas 51, 52, which restrict its motion. Translation of
stage 41 up and down (toward and away from stops 58, 59) is
similarly limited by stops 58, 59. All rotations of stage 41 are
limited by either mesas 51, 52 or stops 58, 59.
More particularly, undesirable pitching motion (rotation about the
horizontal or lateral axis, which is orthogonal to the direction of
travel) results in up and down vertical motion of the front and
back ends of the stage that is limited by stops 58. Similarly, yaw
motion (rotation about a vertical axis) results in horizontal or
lateral motion of the front and back ends of the stage that is
limited by mesas 51. Similarly, roll motion (rotation about an axis
along the direction of travel) results in vertical motion of the
sides of the stage that is limited by stops 58. Since snubber
assembly 13 inhibits vertical motion of the front and back ends of
stage 41, lateral motion of the front and back ends of the stage
41, and vertical motion of the sides of the stage 41, these three
rotations, i.e., pitch, roll, and yaw, are substantially
inhibited.
Thus, according to at least one aspect of the present invention,
motion control is provided for camera optics or the like wherein
limits on the movement of the optics are defined by a snubber
assembly that can be manufactured, at least in part, using
comparatively low precision techniques. This is because features of
fixed portion or frame 42 of stage assembly 10 are used to align
motion limiting features (such as mesas 51, 52 and stops 58, 59) of
snubber assembly 13. In this manner, the cost of manufacturing the
stage and snubber assembly is substantially mitigated.
Referring now to FIGS. 7 and 8, exemplary structures of a stage
assembly 300, an upper snubber assembly 100, and a lower snubber
assembly 200 are shown. These exemplary structures limit motion of
stage 103 in five degrees of freedom while facilitating
substantially more motion in a sixth degree of freedom, as
indicated by arrow 104. Arrow 104 indicates the directions of
travel of stage 103. That is, arrow 104 indicates the directions
that stage 103 moves so as to effect focusing (or zooming or any
other desired optical effect) of a miniature camera.
Stage assembly 300 cooperates with upper snubber assembly 100 and
lower snubber assembly 200 to provide triaxial snubbing. Thus, both
lateral and axial snubbing is provided for stage 103 and camera
optics mounted thereto.
More particularly, stage 300 is sandwiched or captured between
upper snubber assembly 100 and lower snubber assembly 200. Stage
assembly 300 is configured to facilitate movement of a lens
assembly, such as a focusing or zoom lens assembly, as discussed
above. Upper snubber assembly 100 and lower snubber assembly 200
can be identical with respect to one another.
Both upper snubber assembly 100 and lower snubber assembly 200
comprise mesas 101. Mesas 101 cooperate with potentially abutting
structures of stage 103 to provide both lateral (transverse) and
axial snubbing. Snubbing is provided in one lateral axis by mesas
101 and in the other later axis by other structures of upper
snubber assembly 100 and lower snubber assembly 200. Thus, snubbing
in the two lateral directions (the two directions that are
orthogonal to arrow 104, as indicated by arrows 105 and 109) and
snubbing in the axial direction (the direction of arrow 104) are
provided.
Snubbing in one lateral direction (the transverse or side-to-side
direction indicated by arrow 105 of FIG. 8) is limited by the
snubbing action of surfaces 106 against mesas 101. That is, when
the transverse movement of stage 103 exceeds a predetermined
tolerance, as defined by the distance or gap between surface 106
and mesa 101, then surface 106 abuts mesa 101 and thus limits the
transverse movement of stage 103.
The up-and-down movement (indicated by arrow 109 of FIG. 7) of
wings 107 formed on stage 103 (and thus of stage 103 itself) is
limited by abutting portion 108 of upper snubber assembly 100 and
lower snubber assembly 200. That is, when the up-and-down movement
of stage 103 exceeds a predetermined tolerance, as defined by the
distance or gap between surfaces 108 and wings 107, then wings 107
abuts surfaces 108 and thus limit the upon-and-down movement of
stage 103.
The axial movement (indicated by arrow 104 of FIG. 8) of wings 107
formed on stage 103 (and thus of stage 103 itself) is limited by
abutting portions 110 of wings 107 and mesas 101. That is, when the
axial movement of stage 103 exceeds a predetermined tolerance, as
defined by the distance or gap between surfaces 110 and mesas 101,
then wings 107 abut mesas 101 and thus limit the axial movement of
stage 103.
The stage assembly 103 can be formed of silicon, plastic, or any
other desired material. The snubber assemblies 100 and 200 can be
formed of silicon, plastic, or any other desired material. The
mesas 101 can be formed integrally with the snubber assemblies. The
mesas 106 and/or the entire upper 100 and lower 200 snubber
assemblies can be formed of a material that is softer and/or more
resilient than the material of which the stage assembly 300 is
formed. For example, the stage assembly 103 can be formed of
silicon and the snubber assemblies can be formed of a polymer
material.
Thus, according to this exemplary embodiment of the present
invention, snubbing in three axes is provided in a stage/snubber
assembly 400 without the need for external structures. Snubbing is
provided to the stage 103 prior to the addition of a lens assembly,
so as to mitigate the likelihood of damage to stage assembly 300
during handling and transportation. That is, overtravel or
excessive movement of the stage 103 is limited in a manner that
mitigates damage to the stage assembly 300, as well to any
components attached thereto.
Although the snubber assembly is described herein as being suitable
for controlling the motion of a stage that supports the optics of a
camera, those skilled in the art will appreciate that the stage can
similarly be used to support other items. For example, the stage
can alternatively be used to position a specimen for viewing under
a microscope or for other analysis. Thus, discussing the invention
herein as being useful for positioning the optics of a camera is by
way of example only, and not by way of limitation.
Embodiments described above illustrate, but do not limit, the
invention. It should also be understood that numerous modifications
and variations are possible in accordance with the principles of
the present invention. Accordingly, the scope of the invention is
defined only by the following claims.
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